1. Field of the Invention
The present invention relates to a projection display and, more particularly, to a directional reflection screen that is useful for realizing stereoscopic vision utilizing the binocular parallax effect.
2. Description of the Related Art
Many stereoscopic projection displays offer independent images to the right and left eyes of a viewer, realizing stereoscopic vision based on the binocular parallax effect. "Fundamentals of Three-Dimensional Image" by T. Izumi, pp. 148-160 and "Three-Dimensional Image Engineering" by T. Okoshi, pp. 28 and 91-97, disclose examples of stereoscopic projection displays that realize stereoscopic vision without the need for special eyeglasses.
FIG. 1 illustrates a stereoscopic projection display that combines a directional reflection screen constituted by a corrugated, or "corner-shaped", mirror sheet and a lens sheet having lenses disposed at right angles with respect to the mirrors of the mirror sheet, with separate projection means for right and left image receivers (for example right and left eyes). A large screen can be easily fabricated for the display because the display is of the projection type. In addition, the projected light can be efficiently supplied to a viewing range to offer high brightness since the corrugated mirror sheet features a strong horizontal directional reflection and the lens sheet features a controlled vertical diffusion.
When used with three or more projection means, the directional screen provides a correct image at a viewing point projected from the projection means, and therefore can be applied to a so-called autostereoscopic display. However, the conventional corrugated mirror sheet exhibits such a strong directivity that the viewing range is limited in the horizontal direction, and a sufficiently wide visual zone is not obtained.
When the conventional directional reflection screen is applied to an autostereoscopic display, furthermore, non-viewing regions exist among the viewing ranges of the respective projection means and appear to the viewers as missing image portions.